Tigris-Euphrates Delta: a major source of pesticides to the Shatt al-Arab River (Iraq).

Abstract

Organochlorine pesticides were determined in the Tigris-Euphrates-Shatt al-Arab Delta by high resolution gas chromatography. Mean concentrations of pesticides in the dissolved form were (in ng/L) 98p,p'-DDE; 8o,p'-ODD; 28p,p'-DDD; 16p,p'-DDT; 30 aldrin; 66 dieldrin; 57cis-chlordane; 15trans-chlordane and 10 heptachior. Particulatep,p'-DDE;p,p'-DDT; endrin;cis-chlordane and heptachior mean concentrations at this location were 76, 67, 154, 11, and 68 (Μg/kg, dry weight, respectively. Partitioning of dissolved pesticides was evident along the Shatt al-Arab River, which was reflected by significantly higher levels of particulate species down river. Residues ofp,p'-DDE;p,p'-DDD;p,p'-DDT; endrin and dieldrin were confirmed in sediments from this river (mean concentrations were 19, 4, 3, 7, and 14 Μg/kg, dry weight, respectively); however, DDD was confined to the anoxic sub-surface layers only. Absorbing pesticides from both water and suspended particulate matter, Shatt al-Arab mussels had mean residue concentrations as follows (Μg/kg, wet weight) 43p,p'-DDD; 12o,p'-DDD; 15p,p'-DUT; 166 endrin; 26 aldrin; 24 dieldrin; 6cis-chlordane and 5 trans-chlordane. The Euphrates River was the major source of pesticides in the dissolved form, while the Tigris River contributed pesticides mainly in the particulate form to the Shatt al-Arab River. The sediment of this river was the largest reservoir of organochlorine pesticides, where more than 80% of the studied contaminants reside.